MAINE TOWNSHIP, Ill. (STMW) — When a northwest suburban mother discovered her 18-month-old daughter’s finger had been bitten, she assumed the family pit bull was responsible.

But Cook County sheriff’s police said the culprit was actually another household pet: a piranha, Pioneer Press is reporting.

Police said one of the child’s fingertips was bitten off on the night of June 19 inside the family’s home in the Bay Colony subdivision in unincorporated Maine Township.

Police said the child’s mother reported she heard her daughter crying and noticed the toddler’s finger was bleeding, the fingertip missing.

The mother believed the family’s pit bull had bitten the child, but further investigation by police determined the piranhas, swimming in a fish tank near where the child had been playing, may have been responsible.

Police said the child’s father cut open one of the piranhas, and the piece of his daughter’s finger was recovered from the fish.

The child and the severed part of her finger were taken to Advocate Lutheran General Hospital in Park Ridge.

A spokeswoman for the hospital said she could not disclose information about the child’s treatment, including whether doctors were able to reattach her fingertip.